Hacker News

Mind-reading devices can now predict preconscious thoughts

2025-11-2418:2613388www.nature.com

Ethicists say AI-powered advances will threaten the privacy and autonomy of people who use neurotechnology.

Before a car crash in 2008 left her paralysed from the neck down, Nancy Smith enjoyed playing the piano. Years later, Smith started making music again, thanks to an implant that recorded and analysed her brain activity. When she imagined playing an on-screen keyboard, her brain–computer interface (BCI) translated her thoughts into keystrokes — and simple melodies, such as ‘Twinkle, Twinkle, Little Star’, rang out1.

Casey Harrell (with his wife Levana Saxon) uses his brain implant to generate synthetic speech.Credit: Ian Bates/New York Times/Redux/eyevine

Both Oxley and Matt Angle, chief executive of BCI company Paradromics, based in Austin, Texas, agree that BCIs in brain regions other than the motor cortex might one day help to diagnose and treat psychiatric conditions. Maryam Shanechi, an engineer and computer scientist at the University of Southern California in Los Angeles, is working towards this goal — in part by aiming to identify and monitor neural signatures of psychiatric diseases and their symptoms7.

BCIs could potentially track such symptoms in a person, deliver stimulation that adjusts neural activity and quantify how the brain responds to that stimulation or other interventions. “That feedback is important, because you want to precisely tailor the therapy to that individual’s own needs,” Shanechi says.

Shanechi does not yet know whether the neural correlates of psychiatric symptoms will be trackable across many brain regions or whether they will require recording from specific brain areas. Either way, a central aspect of her work is building foundation models of brain activity. Such models, constructed by training AI algorithms on thousands of hours of neural data from numerous people, would in theory be generalizable across individuals’ brains.


Read the original article

srameshc

Karma: 5624
...
 @Hacker__News
@hacker._news

Comments

  • By pedalpete 2025-11-2421:039 reply

    I believe that training a system to understand the electrical signals that define a movement is significantly different from a system that understands thought.

    I work in neurotech, I don't believe that the electrical signals of the brain define thought or memory.

    When humans understood hydro-dynamics, we applied that understanding to the body and thought we had it all figured out. The heart pumped blood, which brought nutients to the organs, etc etc.

    When humans discovered electricity, we slapped ourselves on the forehead and exclaimed "of course!! it's electric" and we have now applied that understanding on top of our previous understanding.

    But we still don't know what consciousness or thought is, and the idea that it is a bunch of electrical impulses is not quite proven.

    There are electrical firing of neurons, absolutely, but do they directly define thought?

    I'm happy to say we don't know, and that "mind-reading" devices are yet un-proven.

    A few start-ups are doing things like showing people images while reading brain activity and then trying to understand what areas of the brain "light-up" on certain images, but I think this path will prove to be fruitless in understanding thought and how the mind works.

    • By Night_Thastus 2025-11-2421:321 reply

      Agree completely. The brain is so incredibly complex that we've barely scratched the surface. It's not just neurons, which are very complex and vary wildly in genetics between them - it's hundreds of other helper cells all interacting with each other in sometimes bizarre ways.

      To try to boil down it all to any simple signal is just never going to work. If we want to map consciousness it's going to be as complex as simulating it ourselves, creating something as dense and detailed as a real brain.

    • By quantummagic 2025-11-2421:391 reply

      > There are electrical firing of neurons, absolutely, but do they directly define thought?

      Well, surgeons and researchers have shown that electrical stimulation of certain brain regions, can induce "perception" during procedures. They can make a patient have the conscious experience of certain smells, for instance.

      It's not conclusive proof of anything, but I wouldn't bet against us getting closer to the mark, than we were when we only considered hydro-dynamics as the model.

    • By PaulRobinson 2025-11-2421:154 reply

      We know that the brain is a structure that works through electrochemical reactions. Synapses transmit signals sent by axons to neurons. We can test this. We can measure it. There's nothing else going on that we can describe using known science.

      Ah, we might say, maybe there is an unknown science - we did not know about so much before, like electricity, like X-Rays, like quantum physics, and then we did, and the World changed.

      The difference is that we observed something that science could not explain, and then we found the new science that explained it, and a new science was born.

      It's pretty clear to me - but you may know more - that we can explain all brain activity through known science. It might be hard to think of us as nothing more than a bunch of electrochemical reactions in a real-world reinforcement learning system, but that's what we are: there's no gap that needs new science, is there?

      • By lukeinator42 2025-11-2423:45

        Scalp-recorded EEG does not measure action potentials, it can only measure the graded potentials of basically one type of neuron (pyramidal cells) in the cortex, which is a really tiny percentage of both neurons and electrical activity in the brain. Additionally, there is also the various roles neurotransmitters play in the brain, etc., and glial cells seem to also play an important role. So, it’s definitely not the case that there aren’t any gaps that need new science, and even if there weren’t, it’s a pretty big stretch from there to decoding all brain activity solely through the electrical component.

      • By estimator7292 2025-11-2422:31

        No, none of this is settled. We cannot adequately explain brain function with current science.

        There have been studies this year implying that some brain functions rely on quantum interactions.

      • By jaapz 2025-11-2422:261 reply

        Can we? We can only see whatever we can measure with the tools we currently have, which are based on the knowledge we currently have. Who's to say there isn't something out there we haven't discovered yet? There's more than enough we still don't understand in many domains of science

        • By smallnix 2025-11-2423:441 reply

          > Who's to say there isn't something out there we haven't discovered yet

          Occam's razor? We should work with as few assumptions as possible to get a model with the largest scope. Otherwise we get stuck with a hard to falsify mess.

          • By RHSeeger 2025-11-253:27

            Yeah, but "we've been discovering new things for all of history, so there's likely more to discover" seems to a pretty fair assumption.

      • By yeahthereiss 2025-11-2421:42

        [dead]

    • By layer8 2025-11-2423:121 reply

      One thing is probably true: You have to train on the individual person, and it’s not transferable to a different person. Similar to how when taking an LLM and training on the fluctuations of its neural network to “read its thoughts”, the training results won’t transfer to interpreting the semantic contents of the network activity of a different LLM.

      So you probably can’t build a universal mind-reading device.

      • By JamesBarney 2025-11-2423:451 reply

        You can't build a universal mind-reading device that doesn't require calibration.

        • By jaybrendansmith 2025-11-252:18

          And when you can build one, you will also get telepathy, telekinesis, clairaudience and clairvoyance. I can't wait until I can send a directed thought to someone else.

    • By baxtr 2025-11-2421:401 reply

      This sounds logical and convincing.

      At the same time, it should also be easy to falsify.

      Has there been an experimental setup like this tested? If I’m not mistaken it should falsify your claim.

      Train a decoder on rich neural recordings, then test it on entirely new thoughts chosen under blinded conditions.

      If it can still recover the precise unseen content from signals alone, the claim that electrical activity is insufficient is overturned.

      • By plastic-enjoyer 2025-11-2421:57

        > Train a decoder on rich neural recordings, then test it on entirely new thoughts chosen under blinded conditions.

        There have been enough studies about this and the result is mostly the same: it's difficult to nearly impossible to reliable decode neural recordings that differ from the distribution of neural recordings that the decoder was trained on. There are a lot of reasons why this happens, electrical activity being insufficient is not one of them.

    • By PunchyHamster 2025-11-2421:39

      seems like trying to take a single pixel signal (so to speak) and interpolate entire image out of it.

    • By dboreham 2025-11-253:27

      > I don't believe that the electrical signals of the brain define thought or memory.

      Yes and no. It'll be something like a JPEG file. You can have a JPEG file that contains an image of a cat. But give that file to someone who has no clue about JPEG encoding and the file looks like random noise. They'll take 100 years to figure out it's an image of a cat.

      Actually it's like if you take an electron beam prober to one of the NVidia AI GPU chips while it's figuring out whether it likes Wordsworth poetry.

    • By fainpul 2025-11-2421:13

      Does it make sense to think of thoughts, consciousness etc. as an emergent property of the neuronal activity in our brains?

    • By observationist 2025-11-2421:473 reply

      This is silly. It's the sum of electrical and chemical network activity in the brain. There's nothing else it can be. We've got a good enough handle on physics to know that it's not some weird quantum thing, it's not picking up radio signals from some other dimension, and it's not some sort of spirit or mystical phlogiston.

      Your mind is the state of your brain as it processes information. It's a computer, in the sense that anything that processes information is a computer. It's not much like silicon chips or the synthetic computers we build, as far as specific implementation details go.

      There's no scientific evidence that anything more is needed to explain everything the mind and brain does. Electrical and chemical signaling activity is sufficient. We can induce emotions, sights, sounds, smells, memories, moods, pleasure, pain, and anything you can experience through targeted stimulation of neurons in the brain. The scale of our experiments has been gross, only able to read and write from large numbers of neurons, but all the evidence is consistent.

      There's not a single rigorously documented phenomenon, experiment, or any data in existence that suggests anything more than electrical and chemical signaling is needed to explain the full and wonderful and awe-inspiring phenomenon of the human mind.

      It's the brain. We are self constructing software running on 2lb chunks of fancy electric meat stored in a bone vat with a sophisticated network of sensors and actuators in a wonderful biomechanical mobility platform that empowers us to interact with the world.

      It explains consciousness, intelligence, qualia, and every other facet and nuance of the phenomena of mind - there's no need to tack on other explanations. It'd be like insisting that gasoline also requires the rage of fire spirits in order to ignite and power combustion engines - once you get to the point of understanding chemical combustion and expansion of gases and transfer of force, you don't need the fire spirits. They don't bring anything to the table. The scientific explanation is sufficient.

      Neocortical networks, with thalamic and hippocampal system integrations, are sufficient to explain the entirety of human experience, in principle. We don't need fire spirits animating cortical stacks, or phlogiston or ether or spirit.

      Could spirit exist as a distinct, separate phenomenon? Sure. It's not intrinsic to subjective experience, consciousness, and biological intelligence, though, and we should use tools of rational thinking when approaching these subjects, because a whole lot of pseudo-scientific BS gets passed as legitimate scientific and philosophical discourse without having any firm grounding in reality.

      We are brains in bone vats - nothing says otherwise. Unless or until there's evidence to the contrary, let that be enough.

      • By Night_Thastus 2025-11-2421:541 reply

        I think you misunderstood the person you're responding to. They did not say there was some higher force beyond the physical pieces.

        What they're saying is that the brain is really really complicated and our understanding of biology is far too rudimentary right now to be saying "yes, absolutely, 100% sure that we know the nature of consciousness from this one measurement of one type of signal".

        * Neurons are very complex and all have unique mutations from one another

        * Hundreds of other types of cells in the brain interact with them and each other in ways we don't understand

        * The various other parts of the body chemically interact with the brain in ways we don't understand yet, like the gut microbiome

        Trying to flatten all of consciousness to one measurement is just not sufficient. It's like trying to simulate the entire planet as a perfect sphere of uniform density. That works OK for some things but falls apart for more complex questions.

        • By observationist 2025-11-2422:18

          I get that, but there's no need to complicate things unnecessarily.

          I'll make an even stronger claim, that biological brains are not only computers, but that they operate in binary, as well. Active and inactive - the mechanisms that trigger activation are incredibly nuanced and sophisticated, but the transfer of information through the network of biological neurons is a matter of zeroes and ones. A signal happens, or doesn't. Intensity, from a qualia persepective, ends up being a matter of frequency and spread, as opposed to level of stimulation. That, in conjunction with all sorts of models of brain function, is allowing neuroscience to make steady, plodding progress in determining the function and behavior of different neurons, networks, clusters, and types in the context in which they are found.

          All else being equal, at the rate neuroscience is proceeding, we should be able to precisely simulate a human brain, in functionally real-time, using real brain networks as models, by around 2040. We should have a handle on every facet of brain chemistry, networking, electrical signaling, and individual neuronal behavior based on a comprehensive and total taxonomy of feature types down to the molecular level.

          Figure out the underlying algorithms and you can migrate those functional structures to purely code. If you can run a mind on code, then it doesn't matter whether you're executing a sequence of computations in a meat brain, in a silicon chip, or using a billion genetically engineered notebook monkeys to painstakingly and tediously do the computations and information transfer manually, passing sheets of paper between them. ( the monkeys, of course, could not operate in real time.)

          There won't be another significant phase change, like we saw from hydraulics to computation equivalence. Computation is what it actually, physically is, at the level of electrical signals and molecular behaviors. It's just extremely complex and sophisticated and elegantly interwoven with the rest of the human organism.

          Brain gut interactions aren't necessary for human subjective experience or cognition. You could remove your brain entirely from your skull, while maintaining a equivalent level of electrical and chemical signaling from an entirely artifical platform of some sort, and as long as the interface between the biological and synthetic maintains the same signaling frequency, chemistry, and connectivity, then it doesn't matter what's on the synthetic end.

          There are independently intelligent aspects to things like the gut biome, and other complex biological systems. Those aren't necessary for brains to do what brains do, except in a supportive role. Decouple the nutrition and evolutionary drives from the mind, and you're left with a fairly small chunk of brain - something like 5B neocortical neurons is the bare minimum of what you'd need to get human level intelligence. Everything on top of that is nice to have, but not strictly necessary from a proof of concept perspective.

      • By wat10000 2025-11-251:211 reply

        There’s nothing in known physics that explains consciousness. I agree about the rest, but consciousness not only defies explanation by known physics, it’s so far beyond what’s known that there isn’t even any concept of what it could be. We barely have the ability to describe it, let alone explain it.

        • By foobarian 2025-11-253:22

          Consciousness is very interesting because if you postulate that you can't possibly create it by running a Turing machine, then anything that is simulatable can't be the mechanism behind it. Which would raise the followup question, what is? My money is on some quantum effect.

      • By HAL3000 2025-11-252:02

        > Neocortical networks, with thalamic and hippocampal system integrations, are sufficient to explain the entirety of human experience, in principle.

        Where did you get that? That's not an established scientific theorem, it's a philosophical stance (strong physicalist functionalism) expressed as if it were empirical fact. We cannot simulate a full human brain at the correct level of detail, record every spike and synaptic change in a living human brain and we do not have a theory that predicts which neural organizations are conscious just from first principles of physics and network topology.

        > We can induce emotions, sights, sounds, smells, memories, moods, pleasure, pain, and anything you can experience through targeted stimulation of neurons in the brain

        That shows dependence of experience on brain activity but dependence is not the same thing as reduction or explanation. We know certain neural patterns correlate with pain, color vision, memories, etc. we can causally influence experience by interacting with the brain.

        But why any of this electrical/chemical stuff is accompanied by subjective experience instead of just being a complex zombie machine? The ability to toggle experiences by toggling neurons shows connection and that's it, it doesn't explain anything.

        > We've got a good enough handle on physics to know that it's not some weird quantum thing, it's not picking up radio signals from some other dimension, and it's not some sort of spirit or mystical phlogiston.

        We do have a good handle on how non conscious physical systems behave (engines, circuits, planets, whatever) But we don't have any widely accepted physical theory that derives subjective experience from physical laws. We don't know which physical/computational structures (if any) are sufficient and necessary for consciousness.

        You are assuming without any evidence that current physics + it's "all computation" already gives a complete ontology of mind. So what is the consciousness? define it with physics, show me equations, you can't.

        > It's a computer, in the sense that anything that processes information is a computer. It's not much like silicon chips or the synthetic computers we build, as far as specific implementation details go.

        We design transformer architectures, we set the training objectives, we can inspect every weight and activation of a LLM. Yet even with all that access, tens of thousands of ML PhDs,years of work and we still don't fully understand why these models generalize the way they do, why they develop certain internal representations and how exactly particular concepts are encoded and combined.

        If we struggle to interpret a ~10^11 parameter transformer whose every bit we can log and replay, it's a REAL hubris to act like we've basically got a 10^14-10^15 synapse constantly rewiring, developmentally shaped biological network to the point of confidently saying "we know there's nothing more to mind than this, case closed lol".

        Our ability to observe and manipulate the brain is currently far weaker than our ability to inspect artificial nets and even those are not truly understood at a deep mechanistic concept level explanatory sense.

        > Your mind is the state of your brain as it processes information.

        Ok but then you have a problem, if anything that processes information is a computer, and mind is "just computation" then which computations are conscious?

        Is my laptop conscious when it runs a big simulation? Is a weather model conscious? Are all supercomputers conscious by default just because they flip bits at scale?

        If you say yes, you've gone to an extreme pancomputationalism that most people (including most physicalists) find extremely implausible.

        If you say no, then you owe a non hand wavy criterion, what's the principled difference, in purely physical/computational terms between a conscious system (human brain) and a non conscious but still massively computational system (weather simulation, supercomputer cluster)? That criterion is exactly the kind of thing we don't have yet.

        So saying "it’s just computation" without specifying which computations and why they give rise to a first person point of view leaves the fundamental question unanswered.

        And one more thing your gasoline analogy is misleading, combustion never presented a "hard problem of combustion" in the sense of a first person, irreducible qualitative aspect. People had wrong physical theories, but once chemistry was in place, everything was observable from the outside.

        Consciousness is different, you can know all the physical facts about a brain state and still not obviously see why it should feel like anything at all from the inside.

        That's why even hardcore physicalist philosophers talk about the "explanatory gap". Whether or not you think it's ultimately bridgeable, it's not honest to say the gap is already closed and the scientific explanation is "sufficient".

  • By Terr_ 2025-11-2418:413 reply

    From some dystopic device log:

        [alert] Pre-thought match blacklist: 7f314541-abad-4df0-b22b-daa6003bdd43
    [debug] Perceived injustice, from authority, in-person
    [info]  Resolution path: eaa6a1ea-a9aa-42dd-b9c6-2ec40aa6b943
    [debug] Generate positive vague memory of past encounter
    Not a reason to stop trying to help people with spinal damage, obviously, but a danger to avoid. It's easy to imagine a creepy machine argues with you or reminds you of things, but consider how much worse it'd be if it derails your chain of thought before you're even aware you have one.

  • By guiand 2025-11-2419:001 reply

    Split brain experiments show that a person rationalizes and accommodates their own behavior even when "they" didn't choose to perform an action[1]. I wonder if ML-based implants which extrapolate behavior from CNS signals may actually drive behavior that a person wouldn't intrinsically choose, yet the person accommodates that behavior as coming from their own free will.

    [1]: "The interpreter" https://en.wikipedia.org/wiki/Left-brain_interpreter

    • By brnaftr361 2025-11-2419:073 reply

      Split brain experiments have been called into question.[0]

      [0]: https://www.sciencedaily.com/releases/2017/01/170125093823.h...

      • By comboy 2025-11-2420:091 reply

        > The patients could accurately indicate whether an object was present in the left visual field and pinpoint its location, even when they responded with the right hand or verbally. This despite the fact that their cerebral hemispheres can hardly communicate with each other and do so at perhaps 1 bit per second

        1 bit per second and we are passing complex information about location in 3d space?

        • By vilhelm_s 2025-11-2420:581 reply

          Yeah, that sounds very unlikely. The full paper dismisses the possibility:

          > Another possible explanation to consider is that the current indings were caused by cross-cueing (one hemisphere informing the other hemisphere with behavioural tricks, such as touching the left hand with the right hand). We deem this explanation implausible for four reasons. First, cross-cueing is thought to only allow the transfer of one bit of information (Baynes et al., 1995). Yet, both patients could localize stimuli throughout the entire visual field irrespective of response mode (Experiments 1 and 5), and localizing a stimulus requires more than one bit of information. Second, [...]

          I get the impression that the authors of the paper have some kind of woo (nonmaterialist) view of consciousness. But they also mention this possiblity, which seems more plausible to me:

          > Finally, a possibility is that we observed the current results because we tested these patients well after their surgical removal of the corpus callosum (Patient DDC and Patient DDV were operated on at ages 19 and 22 years, and were tested 10–16 and 17–23 years after the operation, respectively). This would raise the interesting possibility that the original split brain phenomenon is transient, and that patients somehow develop mechanisms or even structural connections to re-integrate information across the hemispheres, particularly when operated at early adulthood.

          • By throw310822 2025-11-250:11

            > I get the impression that the authors of the paper have some kind of woo (nonmaterialist) view of consciousness.

            Indeed:

            "Our findings, however, reveal that although the two hemispheres are completely insulated from each other, the brain as a whole is still able to produce only one conscious agent."

            Which is materially impossible, given the premise.

      • By pinkmuffinere 2025-11-2419:322 reply

        Wow this is fascinating, and gets rid of one of my eldritch memetic horrors. Thanks for sharing, I’m going to submit it as its own post as well!

      • By empath75 2025-11-2419:491 reply

        That's a great paper, but I don't think it calls into question anything about post-hoc rationalizations, and it might actually put that idea on more solid ground.

        • By debo_ 2025-11-2419:50

          Maybe you are just rationalizing it.

HackerNews

About